Contemporary interest in using tethered aerostats to carry and execute various surveillance and communication missions is growing. Unlike fixed-wing aircrafts or helicopters, these aerostats use helium or hydrogen to stay aloft. They are unmanned, inexpensive, and anchored to the ground by a tethering system that also provides power and communication.
Webster's Dictionary defines the term “service load” as the “load a structure is expected to support under normal usage”.
A tethered aerostat is designed to elevate and keep a service load at a predetermined deployment altitude in the Earth's atmosphere. Its lifting force should be sufficient to support its own weight, the weight of the tether, and the weight of a service load. Because tether's weight increases with altitude, an aerostat's operational altitude and its maximum service load are capped by design.
Also, a tethered aerostat is subject to wind migration; the wind will push away the aerostat from the ideal vertical deployment position. In order to keep the same altitude, the aerostat's tether must be longer, and because it is moving away from the vertical position the tether will also develop slack. The stronger the wind, the larger the migration from the vertical deployment position; the larger the tether's slack, the larger the tether's weight. This additional weight will pull down the aerostat from its initial altitude.
The present invention relates to a service load neutral, self-stabilizing Airborne Elevator Apparatus capable of deploying at the same time multiple service loads at different altitudes in the Earth's atmosphere.
To explain the present invention's service load neutrality feature, a comparison to a regular elevator is in order.
In most basic embodiment the Airborne Elevator Apparatus is comprised of:                Airborne means for positioning the apparatus in the Earth's atmosphere,        Airborne means for deploying at the same time multiple service loads at different altitudes along said positioning means, and        Means for controlling the apparatus in operation.In comparison, a non-airborne elevator would have:        Means for positioning the elevator adjacent or within a building structure, represented by the elevator's vertical shaft built around a building structure and the guiding rails attached to the shaft,        Means for deploying a service load, represented by the elevator's cabin and its means of moving up and down on the guiding rails of the elevator's shaft, and        Means for controlling the position of the elevator's cabin, represented by several control panels positioned inside the elevator's cabin, and on the floors serviced by the elevator.        
The main novelty of the present invention, outside the fact that its positioning and service load deployment means are airborne, is its service load neutrality feature. This feature offers the equivalent of having several cabins sharing the same guiding rails of a regular elevator without putting any load on the elevator's shaft and implicitly on the building structure.
A search of the prior art did not disclose any patents that read on the instant invention, and none of the prior art related to tethered aerostats can claim to be load neutral or to deploy at the same time multiple service loads at different altitudes in the Earth's atmosphere. However, the following U.S. patents are considered related:
U.S. Pat. No.INVENTORISSUED5,295,625RedfordMar. 22, 19946,227,484MiyakeMay 8, 20016,241,160RedfordJun. 5, 2001
Redford teaches a long, hollow, cylindrical apparatus suspended in the atmosphere by toroidal balloons positioned along its height. The apparatus promotes convective air movements inside it, as a way to collect, transport, and distribute condensed water from the water vapor present in the air moving inside. The apparatus' operational altitude in the atmosphere is controlled by a cable wound on a motorized reel attached to the ground. A Balloon enclosure suspends the apparatus' water vapor condenser. The condenser's surfaces condenses the water vapor ascending inside the apparatus and transfers the collected water to the lower section of the apparatus using a helicoidally shaped pipe system inside the apparatus' cylindrical column. The water moving down through the helicoidally shaped pipe system will also rotate the apparatus around its vertical axis to increase its wind stability in the atmosphere. When the condensed water reaches the bottom of the apparatus it is dispersed to the ground through a water distribution ring.
Miyake teaches a tethered spherical balloon having an envelope inflated with lighter than air gas, a gondola attached to the bottom of the balloon's envelope, a vertical stabilizer attached to the same balloon's envelope, and a connecting assembly to anchor the balloon via a tether to a motorized drum positioned on the ground. The connecting assembly is positioned opposite of the balloon's vertical stabilizer, with the gondola disposed in-between in a vertical plan containing the center of the spherical balloon and its gravity center. This feature gives increased wind stability to the tethered spherical balloon. The vertical stabilizer also gives the balloon's gondola stability in windless conditions. When deployed at lower altitudes in the Earth's atmosphere, below 150 meters, the tethered spherical balloon's gondola remains vertical and relatively motionless even at wind speeds above 7 meters per second. This feature allows cameras positioned in the balloon's gondola to take aerial bird's-eye view photography and video not possible with a regular tethered balloon.
Redford teaches a large diameter, tall, hollow, air transport shuttle tethered from the ground and having a cylindrical shaped tower on its upper section that hosts a cylindrical balloon and the apparatus air exhaust valves, and a variable length conical column on its lower section hosting a large air intake valve. The apparatus suspending system comprises an auxiliary balloon enclosure and a large diameter circular ring balloon positioned around the cylindrical shaped tower, both filled with lighter than air gases. The auxiliary balloon has enough lifting force to support its own weight and the weight of the cylindrical tower. The large diameter circular ring balloon is designed to support its own weight, the weight of the balance of the apparatus including its tether, and to provide additional lifting force to elevate the apparatus at higher altitudes for operational based reasons. The descending of the air transport shuttle to lower altitudes is controlled by the tether wound on a motorized reel attached to the ground. The cylindrical balloon placed inside the apparatus' cylindrical tower, is used to compensate from the variation of outside air density during the ascending and descending cycles of the air transport shuttle. The auxiliary balloon enclosure and the large diameter circular ring balloon have gyro-sails to rotate the apparatus during ascending and descending phases in order to gyroscopically stabilize the apparatus operating under wind conditions. As an inversion layer destabilizer the apparatus loads on its air transport shuttle a large volume of humid air located below an atmospheric inversion layer. By carrying this volume of air to a higher altitude in the atmosphere, the apparatus is dehumidifying and consequently heating the air inside its air transport shuttle. This hot and dry air present inside the air transport shuttle is released at an altitude below the atmospheric inversion layer to trigger the inversion layer's thermal destabilization.